Within the field of Quantum Information Processing, we study two subjects: For quantum state tomography, one common assumption is that the experimentalist possesses a stationary source of identical states. We challenge this assumption and propose a method to detect and characterize the drift of nonstationary quantum sources. We distinguish diffusive and systematic drifts and examine how quickly one can determine that a source is drifting. Finally, we give an implementation of this proposed measurement for single photons. For quantum computing, fault-tolerant protocols assume that errors are of certain types. But how do we detect errors of the wrong type? The problem is that for large quantum states, a full state description is impossible to analyze, and so one cannot detect all types of errors. We show through a quantum state estimation example (on up to 25 qubits) how to attack this problem using model selection. We use, in particular, the Akaike Information Criterion. Our example indicates that the number of measurements that one has to perform before noticing errors of the wrong type scales polynomially both with the number of qubits and with the error size. This dissertation includes previously published co-authored material.

The purpose of this essay is to answer the following questions: Has the increased e-commerce had a negative impact on the inflation, and is the effect decreasing? and: Is there a long term and/or short term effect by the increased e-commerce on the inflation? To answer the first question a fixed effects regression model is applied, based on panel data for 28 European countries for the time period 2006-2017. The regression obtains results that support the hypothesis that the increased e-commerce has had a negative effect on inflation. Furthermore, the result indicates that the effect is decreasing. The second question is answered with the help of an Error Correction Model and time series data for Sweden during the period 2006-2017. The result shows that there is an error correction towards a long run equilibrium and the short term estimates indicate that there is a negative short term effect of the increased e-commerce on inflation. These results are in line with the hypothesis of this essay as well as previous studies that have examined similar questions.

Orientador: José Ricardo Barbosa Gonçalves / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Economia / Made available in DSpace on 2018-08-20T23:39:08Z (GMT). No. of bitstreams: 1 Nunes_LeonardoDias_M.pdf: 2321419 bytes, checksum: 94faaa7fdc7d73f5d56359dabddbd2b6 (MD5) Previous issue date: 2012 / Resumo: Este trabalho procura contribuir para a compreensão da difusão das ideias econômicas considerando a história econômica contemporânea do Brasil. Para tanto, contemplou-se o debate em torno da correção monetária devido ao impacto que este instrumento causou no bojo das reformas implementadas através da política econômica da ditadura militar. Primeiramente apresentamos um panorama da economia nacional a partir dos anos 1960, período marcado pelo baixo crescimento do PIB e alta inflação, caracterizado não só por uma crise econômica, mas também por uma crise de ordem política. Em seguida apresentamos como foram difundidas as ideias econômicas em torno da correção monetária no diário Folha de São Paulo, articulando as notícias publicadas neste diário com a avaliação da literatura existente sobre o tema. E, por fim, apresentamos algumas referências de Mário Henrique Simonsen e Maria da Conceição Tavares acerca do debate ocorrido em torno da correção monetária, em um momento em que o primeiro representava a corrente dos economistas ortodoxos e, a segunda, a corrente dos economistas heterodoxos / Abstract: This work aims to contribute to the comprehension of the diffusion of economic ideas considering the contemporary Brazilian economic history. For that, it was contemplated the debate around of the price level accounting due to the impact which this monetary policy instrument caused in the bulge of the reforms implemented by Dictatorship Regime. Thus primarily it was presented a view of the Brazilian economy after the decade of 1960, period that had a low growth of the GDP and high inflation, characterized by an economic and a political crises. Thereby it was presented how was diffused the economic ideas around the price level accounting in the newspaper Folha de São Paulo. Therefore it was articulated the published news in this newspaper with the existent literature evaluation about the issue. In this part it was presented some ideas of Mário Henrique Simonsen and Maria da Conceição Tavares about the debate occurred around the price level accounting. In that moment, the first one represented the orthodox economists and the second one the heterodox economists / Mestrado / Historia Economica / Mestre em Desenvolvimento Econômico

Abstract Eddy currents and susceptibility differences are the most important sources that interfere with the quality of MR images in the presence of an artificial macroscopic object in the volume to be imaged. In this study, both of these factors have been examined. The findings show that the RF field is the most important cause of induced eddy currents when gradients with relatively slow slew rates are used. The induced eddy currents amplify or dampen the RF field with the result that the flip angle changes. At the proximal end in the vicinity of the hip prosthesis surface, there have been areas where the flip angle is nearly threefold compared to the reference flip angle. Areas with decreased flip angles have also been found near the surface of the prosthesis top. The incompleteness of the image due to eddy currents manifests as signal loss areas. Two different methods based on MRI were developed to estimate the susceptibility of a cylindrical object. One of them is based on geometrical distortions in SE magnitude images, while the other takes advantage of phase differences in GRE phase images. The estimate value of the Profile™ test hip prosthesis is χ = (170 ± 13) 10-6. A remapping method was selected to correct susceptibility image distortions. Correction was accomplished with pixel shifts in the frequency domain. The magnetic field distortions were measured using GRE phase images. The method was tested by simulations and by imaging a hip prosthesis in a water tank and in a human pelvis. The main limitations of the method described here are the loss of a single-valued correction map with higher susceptibility differences and the problems with phase unwrapping in phase images. Modulation transfer functions (MTF) were exploited to assess the effect of correction procedure. The corrected image of a prosthesis in a human hip after total hip arthroplasty appears to be equally sharp or slightly sharper than the corresponding original images. The computer programs written for this study are presented in an appendix.

A systematic method for the design of unsymmetrical optical systems is described. Freeform optical surfaces are constructed by superposition of a conic segment and a polynomial, and successfully applied to design relatively fast wide field-of-view optical systems.

>Magister Scientiae - MSc / Purpose:This research investigates the existence of long-term equilibrium relationships among the stock market indices of Brazil, Russia, India, China and South Africa (BRICS). It further investigates cointegrated stock pairs for possible implementation of statistical arbitrage trading techniques.Design:We utilize standard multivariate time series analysis procedures to inspect unit roots to assess stationarity of the series. Thereafter, cointegration is tested by the Johansen and Juselius (1990) procedure and the variables are interpreted by a Vector Error Correction Model (VECM). Statistical arbitrage is investigated through the pairs trading technique.Findings:The five stock indices are found to be cointegrated. Analysis shows that the cointegration rank among the variables is significantly influenced by structural breaks. Two pairs of stock variables are also found to be cointegrated. This guaranteed the mean reversion property necessary for the successful execution of the pairs trading technique. Determining the optimal spread threshold also proved to be highly significant with respect to the success of this trading technique.Value:This research seeks to expand on the literature covering long-run co-movements of the volatile emerging market indices. Based on the cointegration relation shared by the BRICS, the research also seeks to encourage risk taking when investing. We achieve this by showing the potential rewards that can be realized through employing appropriate statistical arbitrage trading techniques in these markets.

Tumor functional volume (FV) and its mean activity concentration (mAC) are the quantities derived from positron emission tomography (PET). These quantities are used for estimating radiation dose for a therapy, evaluating the progression of a disease and also use it as a prognostic indicator for predicting outcome. PET images have low resolution, high noise and affected by partial volume effect (PVE). Manually segmenting each tumor is very cumbersome and very hard to reproduce. To solve the above problem I developed an algorithm, called iterative deconvolution thresholding segmentation (IDTS) algorithm; the algorithm segment the tumor, measures the FV, correct for the PVE and calculates mAC. The algorithm corrects for the PVE without the need to estimate camera’s point spread function (PSF); also does not require optimizing for a specific camera. My algorithm was tested in physical phantom studies, where hollow spheres (0.5-16 ml) were used to represent tumors with a homogeneous activity distribution. It was also tested on irregular shaped tumors with a heterogeneous activity profile which were acquired using physical and simulated phantom. The physical phantom studies were performed with different signal to background ratios (SBR) and with different acquisition times (1-5 min). The algorithm was applied on ten clinical data where the results were compared with manual segmentation and fixed percentage thresholding method called T50 and T60 in which 50% and 60% of the maximum intensity respectively is used as threshold. The average error in FV and mAC calculation was 30% and -35% for 0.5 ml tumor. The average error FV and mAC calculation were ~5% for 16 ml tumor. The overall FV error was ~10% for heterogeneous tumors in physical and simulated phantom data. The FV and mAC error for clinical image compared to manual segmentation was around -17% and 15% respectively. In summary my algorithm has potential to be applied on data acquired from different cameras as its not dependent on knowing the camera’s PSF. The algorithm can also improve dose estimation and treatment planning.

The atmosphere distorts the spectrum of remotely sensed data, negatively affecting all forms of investigating Earth's surface. To gather reliable data, it is vital that atmospheric corrections are accurate. The current state of the field of atmospheric correction does not account well for the benefits and costs of different correction algorithms. Ground spectral data are required to evaluate these algorithms better. This dissertation explores using cameras as radiometers as a means of gathering ground spectral data. I introduce techniques to implement a camera systems for atmospheric correction using off the shelf parts. To aid the design of future camera systems for radiometric correction, methods for estimating the system error prior to construction, calibration and testing of the resulting camera system are explored. Simulations are used to investigate the relationship between the reflectance accuracy of the camera system and the quality of atmospheric correction. In the design phase, read noise and filter choice are found to be the strongest sources of system error. I explain the calibration methods for the camera system, showing the problems of pixel to angle calibration, and adapting the web camera for scientific work. The camera system is tested in the field to estimate its ability to recover directional reflectance from BRF data. I estimate the error in the system due to the experimental set up, then explore how the system error changes with different cameras, environmental set-ups and inversions. With these experiments, I learn about the importance of the dynamic range of the camera, and the input ranges used for the PROSAIL inversion. Evidence that the camera can perform within the specification set for ELM correction in this dissertation is evaluated. The analysis is concluded by simulating an ELM correction of a scene using various numbers of calibration targets, and levels of system error, to find the number of cameras needed for a full-scale implementation.

Although motion correction in medical imaging is well established and has attracted much interest and research funding, a gap still exists in that there is a lack of reliable, low-cost hardware to enable such techniques to be widely adopted in healthcare. Motion correction of brain Positron Emission Tomography (PET) data for instance is an important step in realising the potential offered by modern high resolution PET scanners. Since it is not likely that subjects can remain stationary throughout the PET scan, which can last 60 minutes or more, accurate and reliable motion tracking is needed to correct the PET data for any observed motion. A commercially available marker based motion tracking system was evaluated and found to produce unreliable data. This was due to the possibility of the tracking tool slipping from the subject. This thesis describes the investigations into alternative and novel tracking techniques for use in PET. These included a markerless tracking system using the Microsoft Kinect (a low cost depth sensor) as well as a multiple target marker tracking system. The performance characteristics of both systems (low cost, high spatial and temporal accuracy, and real-time operation) were evaluated using phantom and clinical experiments. Investigations into using these two tracking techniques in whole body PET, specifically measuring the respiratory rate during lung imaging, were developed and compared against current commercially available solutions.

This dissertation explores the effect of nanometer-scale changes in structure on the energetics of photocatalytic and photovoltaic materials. Of particular interest are semiconductor nanocrystals (NCs), which have interesting chemical properties that lead to novel structures and applications. Chief among these properties are quantum confinement and the high surface area-to-volume ratio, which allow for chemical tuning of the energetics and structure of NCs. This tunable energetic landscape has led to increasing application of NCs in various areas of research, including solar energy conversion, light-emitting diode technologies, and photocatalysis. However, spectroscopic methods to determine the energetics of NCs have not been well developed, due to chemical complexities of relevant NCs such as polydispersity, capping ligand effects, core-shell structures, and other chemical modifications. In this work, we demonstrate and expand the utility of photoelectron spectroscopy (PES) to probe the energetics of NCs by considering the physical processes that lead to background and secondary photoemission to enhance photoemission from the sample of interest. A new methodology for the interpretation of UP spectra was devised in order to emphasize the minute changes to the UP spectra line shape that arise from nanoscopic changes to the NCs. We applied various established subtractions that correct for photon source satellites, secondary photoelectrons, and substrate photoemission. We then investigated the effect of ligand surface coverage on the surface chemistry and density of states at the top of valence band (VB). We systematically removed ligands by increasing numbers of purification steps for two diameters of NCs and found that doing so increased photoemission density at the top of the VB, which is due to undercoordinated surface atoms. Deeper VB structure was also altered, possibly due to reorganization of the atoms in the NC. Using the new UPS interpretation methodology, we examined the evolution of the valence band energy (EVB) of CdSe NCs as it was modified from spherical NC to rod to Au-NP tipped nanorod (NR). We also employed potential-modulated attenuated total reflectance spectroscopy (PM-ATR) to probe the conduction band energy (ECB) of the series. The EVB decreased with each modification, which is predicted with a band-bending model. This trend was also observed in the ECB, as revealed by spectroelectrochemistry, along with the appearance of new metal-semiconductor states in the band gap. UPS was finally used to investigate the even more complex Pt-NP tipped CdSe@CdS core@shell NR heterostructure. The addition of the CdS shell decreases the EVB relative to CdSe, as expected from common cation II-VI compounds. The Pt-NC increases the EVB, which, like the Au-CdSe NR, is predicted by employing a band-bending model. XPS revealed that PtSx-like chemical states were formed near the CdS-Pt interface. These experiments, along with the improved UP spectra interpretation methodology, demonstrate the wealth of information regarding surface chemistry and energetics that can be obtained with PES which can be applied to not only NCs, but also to metal oxide or molecular thin films.